Well I know this is quite an odd request. But for organ schools surely an help, so that young organ students get early acquainted with it. This is specially usefull in 3rd-world lands where germans where specially active, and there this feature will stay for loooong time in use.
You mean, organs with electric register tracker and 1-4 set of additional small buttons for each stop ("Frei Kombination 1-n") and buttons to switch between?
For the moment, you could model such a thing for smaller organ using switches.